Liu Xiaofeng, Qin Xinming, Li Xiangyang, Ding Zijing, Li Xingxing, Hu Wei, Yang Jinlong
Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Nano Lett. 2021 Nov 24;21(22):9816-9823. doi: 10.1021/acs.nanolett.1c03814. Epub 2021 Nov 11.
Two-dimensional (2D) ferromagnets possess astonishing potential in new-concept spintronics. However, most of the reported intrinsic 2D ferromagnets show a low Curie temperature far below room temperature. Here, we propose a series of 2D magnetic covalent and metal organic frameworks (COFs/MOFs) by assembling triangular zigzag graphene quantum dots (TZGDs) with various linkages, involving small-sized TZGDs, nonmetal atoms, magnetic metal atoms, and molecules. Upon first-principles calculations, we demonstrate 2D magnetic semiconductors with an enhanced Curie temperature of up to 472 K can be realized through the strong p(d)-p direct exchange interaction between TZGDs and linkages. Particularly, the TZGD size hardly affects the Curie temperature, whereas linkages can modulate the Curie temperature significantly. The TZGD size and linkages can regulate the electronic and magnetic properties of TZGD-based 2D ferromagnets. Our results confirm the possibility of designing 2D ferromagnets based on TZGDs and motivate the research of 2D ferromagnets on magnetic quantum dots and molecular magnets.
二维（2D）铁磁体在新概念自旋电子学中具有惊人的潜力。然而，大多数已报道的本征二维铁磁体显示出远低于室温的居里温度。在此，我们通过将三角形锯齿形石墨烯量子点（TZGDs）与各种连接基团组装，提出了一系列二维磁性共价和金属有机框架（COFs/MOFs），其中包括小尺寸的TZGDs、非金属原子、磁性金属原子和分子。通过第一性原理计算，我们证明通过TZGDs与连接基团之间强大的p(d)-p直接交换相互作用，可以实现居里温度高达472 K的二维磁性半导体。特别地，TZGD的尺寸几乎不影响居里温度，而连接基团可以显著调节居里温度。TZGD的尺寸和连接基团可以调节基于TZGD的二维铁磁体的电子和磁性性质。我们的结果证实了基于TZGD设计二维铁磁体的可能性，并推动了对磁性量子点和分子磁体上二维铁磁体的研究。
